Re: [PATCH 14/14] hw/i386/vmport: Assert vmport initialized before registering commands

[Liran Alon <liran.alon@oracle.com>]

On 10/03/2020 11:30, Michael S. Tsirkin wrote:
> On Tue, Mar 10, 2020 at 01:54:11AM +0200, Liran Alon wrote:
>> vmport_register() is also called from other modules such as vmmouse.
>> Therefore, these modules rely that vmport is realized before those call
>> sites. If this is violated, vmport_register() will NULL-deref.
>>
>> To make such issues easier to debug, assert in vmport_register() that
>> vmport is already realized.
>>
>> Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com>
>> Signed-off-by: Liran Alon <liran.alon@oracle.com>
>
> Hmm and what does actually make sure it is realized?

port_state global var is only set in vmport_realizefn().

-Liran

>
>> ---
>>   hw/i386/vmport.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/hw/i386/vmport.c b/hw/i386/vmport.c
>> index 95d4a23ce9ba..659a323e8448 100644
>> --- a/hw/i386/vmport.c
>> +++ b/hw/i386/vmport.c
>> @@ -68,6 +68,8 @@ static VMPortState *port_state;
>>   void vmport_register(VMPortCommand command, VMPortReadFunc *func, void *opaque)
>>   {
>>       assert(command < VMPORT_ENTRIES);
>> +    assert(port_state);
>> +
>>       trace_vmport_register(command, func, opaque);
>>       port_state->func[command] = func;
>>       port_state->opaque[command] = opaque;
>> -- 
>> 2.20.1